The present invention relates to expansion devices for refrigerant systems and in particular to a feed device, which has a high efficiency.
In a refrigeration system, the liquid refrigerant from the condenser has a relatively higher pressure than is needed in an evaporator. The feed device must be placed between the condenser and the evaporator so that the refrigerant in the evaporator will boil off at allow temperature to produce cooling. There are a number of requirements for this device. The device must deliver the liquid refrigerant into the evaporator in an amount equal to that required to provide the desired cooling effect. This amount will also prevent the liquid refrigerant from entering the suction line to a compressor when the compressor is off. In addition, the device must have a small pressure drop as the liquid refrigerant moves through it.
In Webber""s U.S. Pat. No. 4,633,681 it is disclosed that in his feed device for the refrigerant system there is a small pressure drop when the liquid refrigerant moves through it. This simple low cost effective device has some disadvantages. It does not prevent the entering of the liquid refrigerant to the suction line when the compressor is off. In addition, the rise in pressure of the steam-generated refrigerant takes place in the condenser when the heating load on the evaporator is increased. This in turn causes overloading of the compressor and excessive power consumption.
There is a need for a feed device, which will have the advantages of the device disclosed in U.S. Pat. No. 4,633,681, but with the prevention of the liquid refrigerant from entering the compressor when it is off and power losses when the heating load on the evaporator is increased.
The present invention provides for the improvement of the refrigerant feed device. The refrigerant feed device for a refrigeration system is comprised of a housing with an inlet containing within it one end with a valve-like structure situated in the bottom part of the housing, and a second end for connection to the liquid line for receiving the liquid refrigerant from a condenser. The housing also consists of an outlet disposed with one end with a valve-like structure set and at least one groove orifice formed in the top part of the housing as well as second end for connection to the liquid line for input of liquid refrigerant to the evaporator. The effective cross-section of the inlet is smaller than the effective cross-section of the outlet, creating pressure differences that cause a movable piston with one convex (conical, spherical or ellipsoidal) end and a second flat end with a cylindrical projection to pass into the cone. The refrigerant feed device by means of its inlet line for receives liquid refrigerant from the condenser and by means of its outlet liquid line discharges liquid refrigerant to the evaporator. In order to improve the operation of the refrigerant system an additional device providing a constant amount of steam-generated refrigerant pressure in the condenser is installed as a by-pass to the refrigerant feed device. A relief valve, a solenoid, or an automatic valve with a set point adjustment can be used as the aforementioned device.